Undercooling Behavior and Solidification Microstructure Evolution of Sn-Cu-Ni Solders Modified by Minute Amount of Mixed Rare Earth La-Ce

Abstract:

Sn-Cu-Ni alloy solders have attracted considerable attention from electronic packaging manufacturers and suppliers owing to silver- and lead-free feature and low-cost advantage of the solders. However, there is still a lack of in-depth understanding on composition optimization and microstructure control of the solders. In the present study, the influences of the addition of a minute amount of mixed rare earth La-Ce, in the range of 0.05-0.50wt%, on melting characteristics, undercooling behavior and solidification microstructure evolution of Sn-0.7Cu-0.05Ni-xMRE (x=0.05, 0.10, 0.25, 0.50wt%) alloy solders were investigated. The results show that the addition of rare-earth La-Ce has brought about an obvious decrease of the undercooling for Sn-Cu-Ni series of solders, consequently the growth of primary solidification phase of Cu(Ni)-Sn type intermetallic compound has been suppressed and the β-Sn phase has exhibited a microstructural transition from dendritic grain to equiaxed grain with increasing the amount of La-Ce added to the solder.

• Periodical: Materials Science Forum (Volumes 654-656)
• Pages: 1373-1376
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.654-656.1373
• Online since: June 2010
• Authors: Min Bo Zhou, Xiao Ma, Xin Ping Zhang
• Keywords: Lead-Free Solder, Micro-Structure Evolution, Mixed Rare Earth La-Ce, Sn-Cu-Ni Alloy, Undercooling

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